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Re: A simpl(e)ification

  • To: mathgroup at smc.vnet.net
  • Subject: [mg105794] Re: A simpl(e)ification
  • From: Peter Breitfeld <phbrf at t-online.de>
  • Date: Sat, 19 Dec 2009 06:26:21 -0500 (EST)
  • References: <hgd7qr$bkk$1@smc.vnet.net>

Simplify doesn't like the b in the denominator (I don't know why), but

Simplify[Im[Exp[-2 I a] 1/b], {a, b} \[Element] Reals && b != 0]

will work. But usually it's easier to use ComplexExpand instead of
Simplify, which treats all variables as Reals.


Pianiel wrote:

> Dear All,
>
> With Mathematica 7.0.1, the following expression;
>
> Simplify[  Im[E^(-2 I a) b],  Assumptions -> Element[a, Reals] &&
> Element[b, Reals]]
>
> gives
>
> -b Sin[2 a]
>
> But:
>
> Simplify[  Im[E^(-2 I a) 1/b],  Assumptions -> Element[a, Reals] &&
> Element[b, Reals]]
>
> gives
>
> Im[E^(-2 I a)/b]
>
> So we see that the Im[] is not simplified. Why?
>
> Any idea how to help mathematica to handle the simplification shown in
> the second example. It seems to be so similar to the first kind...
>
> Thanks in advance
>
> Pianiel
>

-- 
_________________________________________________________________
Peter Breitfeld, Bad Saulgau, Germany -- http://www.pBreitfeld.de


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